Dimethylformamide → 8-bromo-7-fluoro-3-methyl-3,4-dihydroquinoxalin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

A 500 mL round-bottomed flask charged with 3-bromo-4-fluorobenzene-1,2-diamine (600c) (18 g, 88 mmol), DMF (100 mL), ethyl 2-bromopropionate (Sigma Aldrich, 11.54 mL, 89 mmol) and NaHCO3 (7.60 g powder, 90 mmol) was heated to 90° C. with a reflux condenser for 30 min, then at 120° C. for 15 h. The reaction mixture was cooled to RT, treated with brine and extracted with EtOAc (2×200 mL), washed with brine (3×) and dried over Na2SO4, filtered and concentrated affording crude 8-bromo-7-fluoro-3-methyl-3,4-dihydroquinoxalin-2(1H)-one (21.75 g, 84 mmol, 96% yield) as an orange-brown viscous oil. The material was used in the subsequent step without further purification. 1H NMR (400 MHz, DMSO-d6) δ ppm 9.67 (s, 1H) 6.78-6.89 (m, 1H) 6.48-6.78 (m, 1H) 6.07-6.35 (m, 1H) 1.25 (d, J=6.46 Hz, 3H). 19F NMR (377 MHz, DMSO-d6) δ ppm −120.49 (1F, s). m/z (ESI, +ve ion) 259.0/261.0 (M+H)+.

Provenance & Evidence